In former times, fresh water was freely available and was thought by some to be an inexhaustible resource. Many communities provided unlimited supplies of water to commercial and residential consumers at a very low cost. Thus, with water conservation having a low priority, little thought was given to it in the design of water-using appliances.
Currently, a combination of factors such as rising urban populations, diminishing water tables and near drought condition in various parts of the world, have combined to diminish the amount of fresh water available to the public. In response to these factors, the public has become aware of the necessity and in some cases, the urgency of water conservation measures. In this regard, water rates are being implemented in many communities throughout the world.
As a result of such water conservation efforts now taking place, both voluntarily and as a result of legislation, homemakers and business managers alike are actively seeking ways to conserve this precious resource. Manufacturers of water consuming appliances, such as taps, shower handles and dishwashers, are developing new products, which perform efficiently, while consuming less water than earlier models. As a result, new appliances are gradually replacing the older appliances, which may be phased out of service over about a ten year period, for example, this will result in significant water conservation.
Several problems may be encountered when using the conventional water saving devices. One of the problems is that the water pressure out from the water saving devices is typically reduced as a result of reduced water flow. It would be desirable to minimise the reduction of water pressure for a given reduced water flow in order to maintain a perception of sufficient water flow for the consumer.